1. Field of the Invention
The present invention relates to improvements to an apparatus for controlling a throttle valve electronically by an actuator such as an electronic motor in an internal combustion engine.
2. Description of the Background Art
Recently control functions for a multifunction throttle valve of an internal combustion engine include 1) an interlocking with an accelerator pedal depressed by an operator; 2) traction control so as to reduce an opening angle of the throttle valve in order to reduce slip of vehicular tire wheels during a vehicular acceleration; and 3) automatic cruise control so that a constant vehicular speed is maintained with the accelerator pedal open or not depressed. Simultaneously, a fail safe structure is included to suppress an overrun of the engine revolutions with the opening angle of the throttle valve held at a minimum position during a failure of the engine.
A Japanese Patent Application First Publication No. Showa 62-284932, published on Dec. 10, 1987, exemplifies a previously proposed throttle valve opening angle controlling apparatus in which the traction control is carried out.
In the disclosed Japanese Patent Application First Publication, a restricting plate is located between the throttle valve shaft bearing on the motor sice and a gear mechanism transmits the rotation of the motor to the throttle valve shaft. However, in the previously proposed throttle valve opening angle controlling apparatus, since the motor is not covered by a case, it is easier to induce the deterioration of each mechanical part, to permit the entry of foreign matter, and corrosion, and to reduce reliability.
It has also been necessary to have the throttle valve opening angle conttrolling apparatus disposed coaxial with the motor and the throttle valve, causing the overall length of the structure to increase, which may cause an increase in vibration.